Thursday was the seventh anniversary of the terrorist attack on the United States.

As we awoke that Tuesday morning, we were ushered into a new world, a world where an almost underground war exploded to the surface.

The Sept. 11 attacks were a series of coordinated suicide attacks by Islamic extremists belonging to the al-Qaeda movement.

This group had been attacking us – almost unreported really – for years prior to 9-11.

On that morning, terrorists affiliated with al-Qaeda hijacked four commercial passenger jet airliners and the war became an open matter.

We all know the story. The hijackers crashed two of the planes into the Twin Towers of the World Trade Center in New York City, killing everyone on board and many others working in the building, causing both buildings to collapse within two hours, destroying at least two nearby buildings and damaging others.

Hijackers also crashed a third airliner into the Pentagon, while the fourth plane crashed into a field near Shanksville in rural Somerset County, Penn., after some of its passengers and flight crew attempted to retake control of the plane.

On that day, 2,974 people died. Another 24 are missing and presumed dead. The overwhelming majority of casualties were civilians, including nationals of over 90 different nations.

The attacks led the United States to launch a War on Terrorism, invading Afghanistan to depose the Taliban, who had harbored al-Qaeda terrorists, and enacting the USA Patriot Act.

We also attacked Iraq and deposed Saddam Hussein.

There were many ceremonies across the nation, including one at Los Alamos National Laboratory, which has a memorial with a piece of the Pentagon as a memorial near the Otowi Building.

Today, there is a small memorial at the Pentagon, but in New York, rebuilding the World Trade Center site has proven more difficult, with controversy over designs and construction have all led to delays to the final plans.

But memorial or not, this is a day will forever be burned in our minds and hearts and should never be forgotten.